Thursday, December 15, 2011

Could Be A Shower/Flurry South Friday Night

Not to pass up the opportunity to let you know about the chance of some precipitation in parts of the region on Friday night but a weak clipper type low will scoot east in the wake of tonight's arriving cool front, crossing to the south of Philadelphia on Friday night and early Saturday morning.  Model trends keep this system, as of now, to the south of Philadelphia, likely to bring no precipitation to anyone north of a Dover-Avalon line.  However, the Cape May and Delaware Beach contingent may have a few drops of rain or perhaps (not likely) a flurry on Friday night with this system.

NAM model from earlier this morning (see above) shows the weak system scooting across Virginia and the Delmarva, bringing steadier showers up into Southern Sussex County in Delaware.  Clouds (dark gray) hold across much of our region.  The temperatures at the surface and at the bottom parts of the atmosphere will be a bit too mild to support snow assuming the computer modeling is correct for this -- generally projected by the NAM to be in the upper 30's or around 40 down there.  The red dashed line is the infamous "540" line that forecasters can use as a way to depict the demarcation between snow and rain in most precipitation scenarios.  The 540 line is north of the precipitation.  It also doesn't help for those down there that want snow that precipitation is projected to be rather light either!

All that said, this little wave doesn't look like it will get into Philadelphia -- the main upper flow aloft is generally keeping this puppy to our south.

Another clipper-type system will cross to our north on Saturday night, probably bringing flurries to the Poconos, perhaps Lehigh Valley.  That system's calling card is simply to feed further energy into the southern wave as it organizes in the Atlantic into a storm system, plus draw in some additional cooler air that will help keep daytime highs on Sunday generally down in the lower half of the 40's.